Aston Martin’s pre-season troubles worsened on Friday after a Honda power unit problem limited their running on the final day of Formula 1 testing in Bahrain.

The Silverstone-based team has completed far fewer laps than rivals, having arrived late for the initial shakedown in Barcelona and struggled with reliability during both Bahrain test sessions.

Honda confirmed that a battery-related issue affected Fernando Alonso’s running in the Adrian Newey-designed car on Thursday.

“Since then, we have been carrying out simulations on the test bench at HRC Sakura,” Honda said. “Due to this and a shortage of power unit components, today’s run plan was very limited, consisting only of short stints.”

Lance Stroll, who was scheduled to drive all day, completed only an installation lap before lunch and did not set a timed lap, compared with Charles Leclerc, who completed 80 laps and topped the timesheets.

Team director Pedro de la Rosa acknowledged the team’s deficit in mileage but highlighted the value of the data collected. “We are not where we wanted to be. We have not done many laps, but we have an enormous amount of data for Australia,” he told Sky Sports.

Alonso, meanwhile, remained confident in Newey’s chassis. “We need to unlock more performance,” he said. “We are still going step by step into the car. We are a little bit on the back foot, we have to admit that, but hopefully there is time to improve. On the chassis, there is no doubt—we have the best with us. After 30-plus years of Adrian Newey dominating the sport, I think no one will doubt that we will find a way to have the best car eventually.”

On the power unit, Alonso added: “We need to wait and see when we unlock all the performance, where we are and what is missing, and then work hard.”

Off the track, Aston Martin shares dropped more than 4% after warning of a larger-than-expected annual loss.

The 2026 F1 season begins in Australia on March 8.